ld/ldcref.c

   1 /* ldcref.c -- output a cross reference table
   2    Copyright 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2006
   3    Free Software Foundation, Inc.
   4    Written by Ian Lance Taylor <ian@cygnus.com>
   5
   6 This file is part of GLD, the Gnu Linker.
   7
   8 This program is free software; you can redistribute it and/or modify
   9 it under the terms of the GNU General Public License as published by
  10 the Free Software Foundation; either version 2 of the License, or
  11 (at your option) any later version.
  12
  13 This program is distributed in the hope that it will be useful,
  14 but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 GNU General Public License for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with this program; if not, write to the Free Software
  20 Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA.  */
  21
  22 /* This file holds routines that manage the cross reference table.
  23    The table is used to generate cross reference reports.  It is also
  24    used to implement the NOCROSSREFS command in the linker script.  */
  25
  26 #include "bfd.h"
  27 #include "sysdep.h"
  28 #include "bfdlink.h"
  29 #include "libiberty.h"
  30
  31 #include "ld.h"
  32 #include "ldmain.h"
  33 #include "ldmisc.h"
  34 #include "ldexp.h"
  35 #include "ldlang.h"
  36
  37 /* We keep an instance of this structure for each reference to a
  38    symbol from a given object.  */
  39
  40 struct cref_ref {
  41   /* The next reference.  */
  42   struct cref_ref *next;
  43   /* The object.  */
  44   bfd *abfd;
  45   /* True if the symbol is defined.  */
  46   unsigned int def : 1;
  47   /* True if the symbol is common.  */
  48   unsigned int common : 1;
  49   /* True if the symbol is undefined.  */
  50   unsigned int undef : 1;
  51 };
  52
  53 /* We keep a hash table of symbols.  Each entry looks like this.  */
  54
  55 struct cref_hash_entry {
  56   struct bfd_hash_entry root;
  57   /* The demangled name.  */
  58   char *demangled;
  59   /* References to and definitions of this symbol.  */
  60   struct cref_ref *refs;
  61 };
  62
  63 /* This is what the hash table looks like.  */
  64
  65 struct cref_hash_table {
  66   struct bfd_hash_table root;
  67 };
  68
  69 /* Forward declarations.  */
  70
  71 static void output_one_cref (FILE *, struct cref_hash_entry *);
  72 static void check_local_sym_xref (lang_input_statement_type *);
  73 static bfd_boolean check_nocrossref (struct cref_hash_entry *, void *);
  74 static void check_refs (const char *, bfd_boolean, asection *, bfd *,
  75                         struct lang_nocrossrefs *);
  76 static void check_reloc_refs (bfd *, asection *, void *);
  77
  78 /* Look up an entry in the cref hash table.  */
  79
  80 #define cref_hash_lookup(table, string, create, copy)           \
  81   ((struct cref_hash_entry *)                                   \
  82    bfd_hash_lookup (&(table)->root, (string), (create), (copy)))
  83
  84 /* Traverse the cref hash table.  */
  85
  86 #define cref_hash_traverse(table, func, info)                           \
  87   (bfd_hash_traverse                                                    \
  88    (&(table)->root,                                                     \
  89     (bfd_boolean (*) (struct bfd_hash_entry *, void *)) (func),         \
  90     (info)))
  91
  92 /* The cref hash table.  */
  93
  94 static struct cref_hash_table cref_table;
  95
  96 /* Whether the cref hash table has been initialized.  */
  97
  98 static bfd_boolean cref_initialized;
  99
 100 /* The number of symbols seen so far.  */
 101
 102 static size_t cref_symcount;
 103
 104 /* Create an entry in a cref hash table.  */
 105
 106 static struct bfd_hash_entry *
 107 cref_hash_newfunc (struct bfd_hash_entry *entry,
 108                    struct bfd_hash_table *table,
 109                    const char *string)
 110 {
 111   struct cref_hash_entry *ret = (struct cref_hash_entry *) entry;
 112
 113   /* Allocate the structure if it has not already been allocated by a
 114      subclass.  */
 115   if (ret == NULL)
 116     ret = ((struct cref_hash_entry *)
 117            bfd_hash_allocate (table, sizeof (struct cref_hash_entry)));
 118   if (ret == NULL)
 119     return NULL;
 120
 121   /* Call the allocation method of the superclass.  */
 122   ret = ((struct cref_hash_entry *)
 123          bfd_hash_newfunc ((struct bfd_hash_entry *) ret, table, string));
 124   if (ret != NULL)
 125     {
 126       /* Set local fields.  */
 127       ret->demangled = NULL;
 128       ret->refs = NULL;
 129
 130       /* Keep a count of the number of entries created in the hash
 131          table.  */
 132       ++cref_symcount;
 133     }
 134
 135   return &ret->root;
 136 }
 137
 138 /* Add a symbol to the cref hash table.  This is called for every
 139    global symbol that is seen during the link.  */
 140
 141 void
 142 add_cref (const char *name,
 143           bfd *abfd,
 144           asection *section,
 145           bfd_vma value ATTRIBUTE_UNUSED)
 146 {
 147   struct cref_hash_entry *h;
 148   struct cref_ref *r;
 149
 150   if (! cref_initialized)
 151     {
 152       if (!bfd_hash_table_init (&cref_table.root, cref_hash_newfunc,
 153                                 sizeof (struct cref_hash_entry)))
 154         einfo (_("%X%P: bfd_hash_table_init of cref table failed: %E\n"));
 155       cref_initialized = TRUE;
 156     }
 157
 158   h = cref_hash_lookup (&cref_table, name, TRUE, FALSE);
 159   if (h == NULL)
 160     einfo (_("%X%P: cref_hash_lookup failed: %E\n"));
 161
 162   for (r = h->refs; r != NULL; r = r->next)
 163     if (r->abfd == abfd)
 164       break;
 165
 166   if (r == NULL)
 167     {
 168       r = xmalloc (sizeof *r);
 169       r->next = h->refs;
 170       h->refs = r;
 171       r->abfd = abfd;
 172       r->def = FALSE;
 173       r->common = FALSE;
 174       r->undef = FALSE;
 175     }
 176
 177   if (bfd_is_und_section (section))
 178     r->undef = TRUE;
 179   else if (bfd_is_com_section (section))
 180     r->common = TRUE;
 181   else
 182     r->def = TRUE;
 183 }
 184
 185 /* Copy the addresses of the hash table entries into an array.  This
 186    is called via cref_hash_traverse.  We also fill in the demangled
 187    name.  */
 188
 189 static bfd_boolean
 190 cref_fill_array (struct cref_hash_entry *h, void *data)
 191 {
 192   struct cref_hash_entry ***pph = data;
 193
 194   ASSERT (h->demangled == NULL);
 195   h->demangled = demangle (h->root.string);
 196
 197   **pph = h;
 198
 199   ++*pph;
 200
 201   return TRUE;
 202 }
 203
 204 /* Sort an array of cref hash table entries by name.  */
 205
 206 static int
 207 cref_sort_array (const void *a1, const void *a2)
 208 {
 209   const struct cref_hash_entry * const *p1 = a1;
 210   const struct cref_hash_entry * const *p2 = a2;
 211
 212   return strcmp ((*p1)->demangled, (*p2)->demangled);
 213 }
 214
 215 /* Write out the cref table.  */
 216
 217 #define FILECOL (50)
 218
 219 void
 220 output_cref (FILE *fp)
 221 {
 222   int len;
 223   struct cref_hash_entry **csyms, **csym_fill, **csym, **csym_end;
 224   const char *msg;
 225
 226   fprintf (fp, _("\nCross Reference Table\n\n"));
 227   msg = _("Symbol");
 228   fprintf (fp, "%s", msg);
 229   len = strlen (msg);
 230   while (len < FILECOL)
 231     {
 232       putc (' ', fp);
 233       ++len;
 234     }
 235   fprintf (fp, _("File\n"));
 236
 237   if (! cref_initialized)
 238     {
 239       fprintf (fp, _("No symbols\n"));
 240       return;
 241     }
 242
 243   csyms = xmalloc (cref_symcount * sizeof (*csyms));
 244
 245   csym_fill = csyms;
 246   cref_hash_traverse (&cref_table, cref_fill_array, &csym_fill);
 247   ASSERT ((size_t) (csym_fill - csyms) == cref_symcount);
 248
 249   qsort (csyms, cref_symcount, sizeof (*csyms), cref_sort_array);
 250
 251   csym_end = csyms + cref_symcount;
 252   for (csym = csyms; csym < csym_end; csym++)
 253     output_one_cref (fp, *csym);
 254 }
 255
 256 /* Output one entry in the cross reference table.  */
 257
 258 static void
 259 output_one_cref (FILE *fp, struct cref_hash_entry *h)
 260 {
 261   int len;
 262   struct bfd_link_hash_entry *hl;
 263   struct cref_ref *r;
 264
 265   hl = bfd_link_hash_lookup (link_info.hash, h->root.string, FALSE,
 266                              FALSE, TRUE);
 267   if (hl == NULL)
 268     einfo ("%P: symbol `%T' missing from main hash table\n",
 269            h->root.string);
 270   else
 271     {
 272       /* If this symbol is defined in a dynamic object but never
 273          referenced by a normal object, then don't print it.  */
 274       if (hl->type == bfd_link_hash_defined)
 275         {
 276           if (hl->u.def.section->output_section == NULL)
 277             return;
 278           if (hl->u.def.section->owner != NULL
 279               && (hl->u.def.section->owner->flags & DYNAMIC) != 0)
 280             {
 281               for (r = h->refs; r != NULL; r = r->next)
 282                 if ((r->abfd->flags & DYNAMIC) == 0)
 283                   break;
 284               if (r == NULL)
 285                 return;
 286             }
 287         }
 288     }
 289
 290   fprintf (fp, "%s ", h->demangled);
 291   len = strlen (h->demangled) + 1;
 292
 293   for (r = h->refs; r != NULL; r = r->next)
 294     {
 295       if (r->def)
 296         {
 297           while (len < FILECOL)
 298             {
 299               putc (' ', fp);
 300               ++len;
 301             }
 302           lfinfo (fp, "%B\n", r->abfd);
 303           len = 0;
 304         }
 305     }
 306
 307   for (r = h->refs; r != NULL; r = r->next)
 308     {
 309       if (! r->def)
 310         {
 311           while (len < FILECOL)
 312             {
 313               putc (' ', fp);
 314               ++len;
 315             }
 316           lfinfo (fp, "%B\n", r->abfd);
 317           len = 0;
 318         }
 319     }
 320
 321   ASSERT (len == 0);
 322 }
 323
 324 /* Check for prohibited cross references.  */
 325
 326 void
 327 check_nocrossrefs (void)
 328 {
 329   if (! cref_initialized)
 330     return;
 331
 332   cref_hash_traverse (&cref_table, check_nocrossref, NULL);
 333
 334   lang_for_each_file (check_local_sym_xref);
 335 }
 336
 337 /* Check for prohibited cross references to local and section symbols.  */
 338
 339 static void
 340 check_local_sym_xref (lang_input_statement_type *statement)
 341 {
 342   bfd *abfd;
 343   lang_input_statement_type *li;
 344   asymbol **asymbols, **syms;
 345
 346   abfd = statement->the_bfd;
 347   if (abfd == NULL)
 348     return;
 349
 350   li = abfd->usrdata;
 351   if (li != NULL && li->asymbols != NULL)
 352     asymbols = li->asymbols;
 353   else
 354     {
 355       long symsize;
 356       long symbol_count;
 357
 358       symsize = bfd_get_symtab_upper_bound (abfd);
 359       if (symsize < 0)
 360         einfo (_("%B%F: could not read symbols; %E\n"), abfd);
 361       asymbols = xmalloc (symsize);
 362       symbol_count = bfd_canonicalize_symtab (abfd, asymbols);
 363       if (symbol_count < 0)
 364         einfo (_("%B%F: could not read symbols: %E\n"), abfd);
 365       if (li != NULL)
 366         {
 367           li->asymbols = asymbols;
 368           li->symbol_count = symbol_count;
 369         }
 370     }
 371
 372   for (syms = asymbols; *syms; ++syms)
 373     {
 374       asymbol *sym = *syms;
 375       if (sym->flags & (BSF_GLOBAL | BSF_WARNING | BSF_INDIRECT | BSF_FILE))
 376         continue;
 377       if ((sym->flags & (BSF_LOCAL | BSF_SECTION_SYM)) != 0
 378           && sym->section->output_section != NULL)
 379         {
 380           const char *outsecname, *symname;
 381           struct lang_nocrossrefs *ncrs;
 382           struct lang_nocrossref *ncr;
 383
 384           outsecname = sym->section->output_section->name;
 385           symname = NULL;
 386           if ((sym->flags & BSF_SECTION_SYM) == 0)
 387             symname = sym->name;
 388           for (ncrs = nocrossref_list; ncrs != NULL; ncrs = ncrs->next)
 389             for (ncr = ncrs->list; ncr != NULL; ncr = ncr->next)
 390               if (strcmp (ncr->name, outsecname) == 0)
 391                 check_refs (symname, FALSE, sym->section, abfd, ncrs);
 392         }
 393     }
 394
 395   if (li == NULL)
 396     free (asymbols);
 397 }
 398
 399 /* Check one symbol to see if it is a prohibited cross reference.  */
 400
 401 static bfd_boolean
 402 check_nocrossref (struct cref_hash_entry *h, void *ignore ATTRIBUTE_UNUSED)
 403 {
 404   struct bfd_link_hash_entry *hl;
 405   asection *defsec;
 406   const char *defsecname;
 407   struct lang_nocrossrefs *ncrs;
 408   struct lang_nocrossref *ncr;
 409   struct cref_ref *ref;
 410
 411   hl = bfd_link_hash_lookup (link_info.hash, h->root.string, FALSE,
 412                              FALSE, TRUE);
 413   if (hl == NULL)
 414     {
 415       einfo (_("%P: symbol `%T' missing from main hash table\n"),
 416              h->root.string);
 417       return TRUE;
 418     }
 419
 420   if (hl->type != bfd_link_hash_defined
 421       && hl->type != bfd_link_hash_defweak)
 422     return TRUE;
 423
 424   defsec = hl->u.def.section->output_section;
 425   if (defsec == NULL)
 426     return TRUE;
 427   defsecname = bfd_get_section_name (defsec->owner, defsec);
 428
 429   for (ncrs = nocrossref_list; ncrs != NULL; ncrs = ncrs->next)
 430     for (ncr = ncrs->list; ncr != NULL; ncr = ncr->next)
 431       if (strcmp (ncr->name, defsecname) == 0)
 432         for (ref = h->refs; ref != NULL; ref = ref->next)
 433           check_refs (hl->root.string, TRUE, hl->u.def.section,
 434                       ref->abfd, ncrs);
 435
 436   return TRUE;
 437 }
 438
 439 /* The struct is used to pass information from check_refs to
 440    check_reloc_refs through bfd_map_over_sections.  */
 441
 442 struct check_refs_info {
 443   const char *sym_name;
 444   asection *defsec;
 445   struct lang_nocrossrefs *ncrs;
 446   asymbol **asymbols;
 447   bfd_boolean global;
 448 };
 449
 450 /* This function is called for each symbol defined in a section which
 451    prohibits cross references.  We need to look through all references
 452    to this symbol, and ensure that the references are not from
 453    prohibited sections.  */
 454
 455 static void
 456 check_refs (const char *name,
 457             bfd_boolean global,
 458             asection *sec,
 459             bfd *abfd,
 460             struct lang_nocrossrefs *ncrs)
 461 {
 462   lang_input_statement_type *li;
 463   asymbol **asymbols;
 464   struct check_refs_info info;
 465
 466   /* We need to look through the relocations for this BFD, to see
 467      if any of the relocations which refer to this symbol are from
 468      a prohibited section.  Note that we need to do this even for
 469      the BFD in which the symbol is defined, since even a single
 470      BFD might contain a prohibited cross reference.  */
 471
 472   li = abfd->usrdata;
 473   if (li != NULL && li->asymbols != NULL)
 474     asymbols = li->asymbols;
 475   else
 476     {
 477       long symsize;
 478       long symbol_count;
 479
 480       symsize = bfd_get_symtab_upper_bound (abfd);
 481       if (symsize < 0)
 482         einfo (_("%B%F: could not read symbols; %E\n"), abfd);
 483       asymbols = xmalloc (symsize);
 484       symbol_count = bfd_canonicalize_symtab (abfd, asymbols);
 485       if (symbol_count < 0)
 486         einfo (_("%B%F: could not read symbols: %E\n"), abfd);
 487       if (li != NULL)
 488         {
 489           li->asymbols = asymbols;
 490           li->symbol_count = symbol_count;
 491         }
 492     }
 493
 494   info.sym_name = name;
 495   info.global = global;
 496   info.defsec = sec;
 497   info.ncrs = ncrs;
 498   info.asymbols = asymbols;
 499   bfd_map_over_sections (abfd, check_reloc_refs, &info);
 500
 501   if (li == NULL)
 502     free (asymbols);
 503 }
 504
 505 /* This is called via bfd_map_over_sections.  INFO->SYM_NAME is a symbol
 506    defined in INFO->DEFSECNAME.  If this section maps into any of the
 507    sections listed in INFO->NCRS, other than INFO->DEFSECNAME, then we
 508    look through the relocations.  If any of the relocations are to
 509    INFO->SYM_NAME, then we report a prohibited cross reference error.  */
 510
 511 static void
 512 check_reloc_refs (bfd *abfd, asection *sec, void *iarg)
 513 {
 514   struct check_refs_info *info = iarg;
 515   asection *outsec;
 516   const char *outsecname;
 517   asection *outdefsec;
 518   const char *outdefsecname;
 519   struct lang_nocrossref *ncr;
 520   const char *symname;
 521   bfd_boolean global;
 522   long relsize;
 523   arelent **relpp;
 524   long relcount;
 525   arelent **p, **pend;
 526
 527   outsec = sec->output_section;
 528   outsecname = bfd_get_section_name (outsec->owner, outsec);
 529
 530   outdefsec = info->defsec->output_section;
 531   outdefsecname = bfd_get_section_name (outdefsec->owner, outdefsec);
 532
 533   /* The section where the symbol is defined is permitted.  */
 534   if (strcmp (outsecname, outdefsecname) == 0)
 535     return;
 536
 537   for (ncr = info->ncrs->list; ncr != NULL; ncr = ncr->next)
 538     if (strcmp (outsecname, ncr->name) == 0)
 539       break;
 540
 541   if (ncr == NULL)
 542     return;
 543
 544   /* This section is one for which cross references are prohibited.
 545      Look through the relocations, and see if any of them are to
 546      INFO->SYM_NAME.  If INFO->SYMNAME is NULL, check for relocations
 547      against the section symbol.  If INFO->GLOBAL is TRUE, the
 548      definition is global, check for relocations against the global
 549      symbols.  Otherwise check for relocations against the local and
 550      section symbols.  */
 551
 552   symname = info->sym_name;
 553   global = info->global;
 554
 555   relsize = bfd_get_reloc_upper_bound (abfd, sec);
 556   if (relsize < 0)
 557     einfo (_("%B%F: could not read relocs: %E\n"), abfd);
 558   if (relsize == 0)
 559     return;
 560
 561   relpp = xmalloc (relsize);
 562   relcount = bfd_canonicalize_reloc (abfd, sec, relpp, info->asymbols);
 563   if (relcount < 0)
 564     einfo (_("%B%F: could not read relocs: %E\n"), abfd);
 565
 566   p = relpp;
 567   pend = p + relcount;
 568   for (; p < pend && *p != NULL; p++)
 569     {
 570       arelent *q = *p;
 571
 572       if (q->sym_ptr_ptr != NULL
 573           && *q->sym_ptr_ptr != NULL
 574           && ((global
 575                && (bfd_is_und_section (bfd_get_section (*q->sym_ptr_ptr))
 576                    || bfd_is_com_section (bfd_get_section (*q->sym_ptr_ptr))
 577                    || ((*q->sym_ptr_ptr)->flags & (BSF_GLOBAL
 578                                                    | BSF_WEAK)) != 0))
 579               || (!global
 580                   && ((*q->sym_ptr_ptr)->flags & (BSF_LOCAL
 581                                                   | BSF_SECTION_SYM)) != 0))
 582           && (symname != NULL
 583               ? strcmp (bfd_asymbol_name (*q->sym_ptr_ptr), symname) == 0
 584               : (((*q->sym_ptr_ptr)->flags & BSF_SECTION_SYM) != 0
 585                  && bfd_get_section (*q->sym_ptr_ptr) == info->defsec)))
 586         {
 587           /* We found a reloc for the symbol.  The symbol is defined
 588              in OUTSECNAME.  This reloc is from a section which is
 589              mapped into a section from which references to OUTSECNAME
 590              are prohibited.  We must report an error.  */
 591           einfo (_("%X%C: prohibited cross reference from %s to `%T' in %s\n"),
 592                  abfd, sec, q->address, outsecname,
 593                  bfd_asymbol_name (*q->sym_ptr_ptr), outdefsecname);
 594         }
 595     }
 596
 597   free (relpp);
 598 }